The use of light emitting diodes (LEDs) to provide light is well known in the field. However, an individual LED generally does not provide sufficient lumen intensity for most residential and commercial uses. To solve this problem, prior art light fixtures use multiple LEDs, often grouping them together in “clusters” to improve the lumen output of a given fixture. The clustering of LEDs, however, results in a diffuse light pattern—often having a beam spread as wide as 160 degrees—which is not appropriate for many applications. Accordingly, conventional LED fixtures are often fitted with reflective cones or lenses that focus the light emitted from each individual LED or LED cluster (for convenience, referred to generally as LED) into a narrower beam, typically resulting in a beam spread ranging from approximately 10 degrees to approximately 60 degrees, depending on the application.
A narrow beam spread generated by an LED may not be sufficient to provide adequate illumination over a broad area. Accordingly, conventional LED fixtures often include multiple LEDs to provide additional light. Such conventional fixtures, however, typically require that each reflective cone or lens for a given LED be aligned in a pre-set direction. Fixing each reflective cone or lens in a pre-set direction effectively locks the pattern of the various light beams during manufacture or assembly.
Locking the direction of the light beams produced by a fixture having multiple LEDs can create a problem after the fixture has been installed. For example, fixed lighting patterns present a particular problem when a fixture is installed in a location (such as an art gallery or retail establishment) and directed at a particular object that may change over time, may move to a different distance from the fixture, and/or may be replaced with objects of different sizes. If the light pattern emanating from the fixture cannot be adjusted, or cannot be adjusted easily, the illuminated object may not be illuminated with the best possible light pattern after it is changed, moved, or replaced.
Accordingly, a need exists for an adjustment mechanism for a light fixture that includes multiple LED light sources capable of providing illumination over a broad area. A need also exists for directing the light from its LED light sources using reflectors or lenses, but should also provide the capability of post-manufacture adjustment of the light pattern emanating from the fixture. Moreover, a need also exists for an adjustment mechanism wherein the process of adjusting the light pattern is simple and does not require significant mechanical aptitude from an individual who is attempting to adjust the light pattern. A further need exists for a light fixture that provides an adjustable light pattern such that the adjustment mechanism can remain fixed in a lighting fixture while providing a light beam that can be adjusted both as to width and focus.